16 By this figment of false philosophy and this shallow and fallacious erudition, joined with a most audacious system of criticism, some have been seduced and "become vain in their thoughts" ( Rom . i. 1), "having rejected good conscience they have made shipwreck concerning the faith" (I Tim . i. 19), they are being tossed about miserably on the waves of doubt, knowing not themselves at what port they must land; others, wasting both time and study, lose themselves in the investigation of abstruse trifling, and thus grow estranged from the study of divine things and of the real springs of doctrine. This hot-bed of error and perdition (which has come to be known commonly as modernism from its craving for unhealthy novelty) although denounced several times and unmasked by the very excesses of its adepts, continues to be a most grave and deep evil. It lurks like poison in the vitals of modern society, estranged as this is from God and His Church, and it is especially eating its way like a cancer among the young generations which are naturally the most inexperienced and heedless. It is not the result of solid study and true knowledge, for there can be no real conflict between reason and faith (Concil. Vatic., Constit. Dei filius , cap. 4). But it is the result of intellectual pride and of the pestiferous atmosphere that prevails of ignorance or confused knowledge of the things of religion, united with the stupid presumption of speaking about and discussing them. And this deadly infection is further fomented by a spirit of incredulity and of rebellion against God, so that those who are seized by the blind frenzy for novelty consider that they are all sufficient for themselves, and that they are at liberty to throw off either openly or by subterfuge the entire yoke of divine authority, fashioning for themselves according to their own caprice a vague, naturalistic individual religiosity, borrowing the name and some semblance of Christianity but with none of its life and truth.
Source: Communium Rerum (Vatican.va)